In a primary cementing operation in a well, a hydraulic cement composition is pumped into an annular space between the wall of the wellbore and the casing. The set cement sheath supports the casing and bonds with the wellbore. The set cement sheath prevents the migration of fluids and gas outside the casing toward the surface of the well.
The set cement sheath must be capable of sustaining high hydrostatic pressure in order to achieve effective zonal isolation. The sheath may fail due to stresses induced by high fluid pressures or high temperatures inside the casing. A high internal pressure results in expansion of the casing, which can cause cracks in the sheath. Similarly, a set cement sheath may be subjected to stresses and fail as a result of creeping of the surrounding subterranean formation.
In order to overcome the stress induced cement failure, elastomeric particulates have been incorporated in the cement composition to enhance the resiliency. Since these materials are solid particles and have a particle size larger than that of the hydraulic cement, silica, and other cement additives, they increase the slurry viscosity.
In general, liquid additives are preferred in some field locations and off shore fields. A copolymer of styrene-butadiene in liquid form (styrene-butadiene latex) is an additive for cement known to increase the resiliency of the set cement to some extent; however, greater resiliency than can be provided by styrene-butadiene latex is desired. Therefore, there is a need to identify a liquid composition that can provide better resiliency to a set hydraulic cement composition.